The present disclosure relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present disclosure relates to commissure attachment features used with collapsible prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size.
When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.
When using collapsible prosthetic heart valves, it may be desirable for the valve to be capable of collapsing (or crimping) to a small profile, such that, when collapsed, it may be contained within a relatively small delivery system. The ability of a collapsible prosthetic heart valve to collapse to a small profile may be at least partially dependent on the amount of material forming the stent supporting the valve. Similarly, the flexibility of the collapsible prosthetic heart valve may be dependent, at least in part, on the amount of material, as well as the geometry of material, in the stent supporting the valve. Increased flexibility may be desirable, for example, because increased flexibility of the collapsible valve may lead to increased flexibility in the delivery system. Increased flexibility in the delivery system may lead to reduced likelihood of vascular trauma or stroke as a result of delivery, and may facilitate the tracking of the aortic arch by the delivery system during delivery. Generally, tracking refers to the ability of the delivery system and/or collapsible prosthetic heart valve to bend or otherwise change shape with respect to the constraints of the anatomy through which they are moving. Preferably, design changes that reduce the profile of the collapsible valve and/or increase flexibility do not significantly negatively affect other characteristics of the valve, such as valve durability and hemodynamics.